HD 332231 b
HD 332231 b is a cold gas giant orbiting HD 332231 in the constellation Cygnus. It lies about 263 light-years from Earth and was discovered in 2020 using the transit method.
How Big Is HD 332231 b?
HD 332231 b has a radius of 9.07 times that of Earth, or 0.81 times the radius of Jupiter. Its mass is 74.1 times that of Earth, giving it a density of 0.55 g/cm³ — closer to gas planets like Jupiter (1.33 g/cm³).
Is HD 332231 b in the Habitable Zone?
HD 332231 b orbits inside the inner edge of the habitable zone of HD 332231. So close to its star, surface conditions are far too hot for liquid water.
Habitable zone of HD 332231: 1.047–2.447 AU (conservative: 1.326–2.320 AU), per Kopparapu et al. (2014). Earth orbits the Sun at 1 AU.
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Temperature on HD 332231 b
The equilibrium temperature of HD 332231 b is about 798 K (525 °C) — hot enough to melt many metals. This estimate ignores any atmosphere, which could change surface temperatures dramatically — Earth's greenhouse effect adds about 33 °C.
Orbit and Year Length
A year on HD 332231 b — one full orbit around HD 332231 — lasts 18.7 Earth days, shorter than Mercury's 88-day year. It orbits at an average distance of 0.145 AU — closer to its star than Mercury is to the Sun.
How Was HD 332231 b Discovered?
HD 332231 b was discovered in 2020 using the transit method, with observations from Transiting Exoplanet Survey Satellite (TESS).
The transit method watches a star for the tiny, regular dip in brightness that occurs when a planet crosses in front of it. The depth and timing of these dips reveal the planet's size and orbital period.
How Far Away Is HD 332231 b?
HD 332231 b is 263.1 light-years (80.7 parsecs) from Earth. Light arriving here tonight left the planet around the year 1763. A probe traveling at the speed of Voyager 1 — about 17 km/s, the fastest outbound spacecraft ever launched — would need roughly 4,630,560 years to make the journey.
Earth Similarity Index
The Earth Similarity Index (ESI) scores how physically similar a planet is to Earth, from 0 to 1, based on radius, density, escape velocity and surface temperature. HD 332231 b scores 0.10, ranking #4,439 of 5,568 planets with a known ESI. For reference, Mars scores about 0.70.
The Host Star: HD 332231
HD 332231
- Surface temperature
- 6,128 K (Sun: 5,772 K)
- Mass
- 1.16 M☉
- Radius
- 1.27 R☉
- Luminosity
- 2.0320 L☉
- Age
- 2.9 billion years (Sun: 4.6)
Planetary System
HD 332231 b is the only planet known to orbit HD 332231 so far.
HD 332231 b — Complete Data
| Radius | 9.073 Earth radii (0.809 Jupiter radii) |
|---|---|
| Mass | 74.10 Earth masses (0.233 Jupiter masses) |
| Density | 0.55 g/cm³ (Earth: 5.51) |
| Orbital period | 18.71 days |
| Orbital distance | 0.145 AU |
| Equilibrium temperature | 798 K (525 °C) |
| Earth Similarity Index | 0.10 |
| Distance from Earth | 263.1 light-years (80.7 parsecs) |
| Constellation | Cygnus |
| Discovery method | Transit |
| Discovery facility | Transiting Exoplanet Survey Satellite (TESS) |
| Discovery year | 2020 |
Data: NASA Exoplanet Archive, last updated 2024-07-23. Earth Similarity Index: PHL @ UPR Arecibo.
Frequently Asked Questions About HD 332231 b
Is HD 332231 b habitable?
No — HD 332231 b orbits too close to its star and is too hot for liquid water to exist on its surface.
How far away is HD 332231 b?
HD 332231 b is about 263 light-years from Earth in the constellation Cygnus. A spacecraft traveling as fast as Voyager 1 (about 17 km/s) would need roughly 4,630,560 years to get there.
How big is HD 332231 b compared to Earth?
HD 332231 b has 9.07 times the radius of Earth and about 74.1 times its mass.
How long is a year on HD 332231 b?
One orbit around HD 332231 takes 18.7 Earth days — short enough that 20 of its years would fit into one Earth year.
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